Transcript Light PPT - plant phys

Light
The Source of all Biological Energy
Trapped in Photosynthesis
Used to determine Seasons
Light: An Energy Waveform With Particle Properties Too
wavelength
violet
400
blue
green yellow orange red
500
600
wavelength (nm)
700 nm
10-9 meter
0.000000001 meter!
Light: An Energy Waveform With Particle Properties Too
wavelength
visible spectrum
400
500
600
wavelength (nm)
700 nm
10-9 meter
0.000000001 meter!
White light: all the colors humans can see at once
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Which side of our
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White Light
Green is reflected!
Leaf Pigments
Absorb Most
Colors
Light: An Energy Waveform With Particle Properties Too
amplitude
brightness
intensity
Many metric units for different purposes
We will use an easy-to-remember English unit: foot-candle
0 fc = darkness
100 fc = living room
1,000 fc = CT winter day
10,000 fc = June 21, noon, equator, 0 humidity
Photomorphogenesis
light
form
Growth in Dark
Etiolated
origin process
Growth in Light
Normal
Short
Tall
Stocky
Thin
Green
White/Yellow
Unexpanded
leaves
Preserve
reserves
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Expanded
leaves
Use
reserves
How deeply
buried am I?
Make Hay!
Gravity!
http://botit.botany.wisc.edu:16080/images/130/Tropisms/Etiolation/Etiolated_-_light_beans_MC_.jpg
Phototropism
light
growth toward act
Darwin 1860s
Went: IAA
IAA
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IAA
perception
by
zeaxanthin
transduction
by IAA
differential
transport
+ growth
response
Photosynthesis: Review and Expansion
CO2 + H2O
light
chlorophyll
O2 + CH2O
Not 1 step…more
like 50!
Light Reactions: perhaps 25 steps
ADP + P + NADP + H2O
light
chlorophyll
Interdependent!
Calvin Cycle Reactions: perhaps 25 steps
ATP + NADPH2 + CO2
In sum:
CO2 + H2O
light
chlorophyll
We have been
hiding considerable
truth from you!
O2 + NADPH2 + ATP
AKA: Dark Reactions
CH2O + NADP + ADP + P
O2 + CH2O
The light and Calvin cycle reactions are interdependent…no dark reactions!
What wavelengths of light drive photosynthesis?
Photosynthetic Rate
100%
0
Action Spectrum
green light
reflected
some still drives
photosynthesis
400
visible spectrum
500
600
wavelength (nm)
700 nm
Light beyond 700 nm
has insufficient energy
to drive photosynthesis
What intensities of light drive photosynthesis?
100%
Reaction Rate
Photosynthesis
add to reserve
grow
reproduce
Respiration
Using reserves
and may die
0
0 10
100
compensation
point
1,000
10,000 fc
Light Intensity (fc)
The example plant shown here “breaks even” at an
intensity we have in our homes…a house plant!
What intensities of light drive photosynthesis?
100%
Reaction Rate
Photosynthesis A
0
Photosynthesis B
Respiration
Shade tolerant
plant dies in
intense light!
0 10
100
compensation
points
1,000
10,000 fc
Light Intensity (fc)
The second example plant shown here cannot survive in
our homes…it is a sun-loving crop plant!
Where in a CT landscape is the light intensity the brightest…the longest?
N
Ferns
Hosta
Impatiens
MOD.
COOL
MOIST Shade all Day! MOIST
W
AM Cool Shade
PM Hot Sun
House
downspout
Daisies
HOT
DRY!
AM Cool Sun
PM Warm Shade
E
downspout
Sun all Day! MOD.
Roses
DRY!
Petunias
PM
AM
S
Where in the house is the light intensity the brightest…the longest?
N
Too Dark!
Sun
Lovers
W
House
General
Houseplants
Shade
Lovers
African Violets
Ferns
Philodendrons
E
Greenhouse Effect!
General Houseplants if Sheer Drapes
PM
AM
S
USDA Hardiness Zones of “Lower 48” States
Note: Willimantic is Zone 6
Where should plants be placed in a CT landscape for winter hardiness?
Winter Wind
N
Exposed
ZONE MORE
4-5 UNIFORM
WINDWARD
INSULATED Shade all Day! COLD
ZONE
5-6
W
AM Cool Shade
PM Hot Sun
House
PM Warm Shade
E
ZONE
6-7
ZONE
2-3
PM
AM Cool Sun
Exposed Sun all Day! LEEWARD
FREEZE
INSULATED
DRY
snow profile
S
AM
Photoperiodism-Sensing Seasons by Daylength
Short Day Plant
Long Day Plant
Noctoperiodism?
Chrysanthemum
Lettuce
Poinsettia
Long Night Plant? Short Night Plant?
Summer (June 21)
16 hr
8 hr
Winter (December 21)
8 hr
8 hr
8 hr
vegetative
flowering
no change
flowering
16 hr
Night Interruption
Spinach
vegetative
reversed
10 sec
W
8 hr
vegetative
flowering
8 hr
vegetative
flowering
Day Interruption
10 sec
8 hr
W
8 hr
Plants measure the length of the night…not the length of the day.
Photoperiodism-Does Light Wavelength Matter?
Control
8 hr
16 hr
Short Day Plant
Long Day Plant
flowering
vegetative
vegetative
flowering
flowering
vegetative
vegetative
flowering
flowering
vegetative
Red 660nm Interruption
8 hr
8 hr
10 sec
R
8 hr
Far-Red 730nm Interruption
8 hr
8 hr
10 sec
FR
8 hr
Sequences Ending in Red
8 hr
10 sec each
8 hr R FR R 8 hr
Sequences Ending in Far-Red
8 hr
10 sec each
8 hr FR R FR 8 hr
Plants use Phytochrome to sense Night Light Status. Pr
Pfr present for significant time in night blocks flowers.
660 nm
730 nm
Pfr*
Photoperiod Applications:
Chrysanthemum Story
Poinsettia Story
LDP Lettuce Problem: Equinoxes
LDP Onions: Bermuda=11+ Sweet Spanish=15+
How long does light need to be on inside house?: Comp Point